Table of contents

• Overview
• Output
• Installation
• Hardware
• Software
• Tested_MCU
• Ports

Overview

• Name : ER_OLEDM1_CH1115
• Title : Library to support the ER-OLEDM1.09-1 128X64 OLED Display Module driven by the CH1115 controller for the Arduino eco-system.
• Description :

1. Arduino eco-system library.
2. Invert colour, vertical rotate, sleep, fade effect, horizontal scroll and contrast control functions supported.
3. 5 ASCII fonts included.
4. Graphics support included.
5. 3 different modes: Multi-buffer , single buffer , no buffer.
6. Bitmaps supported.
7. Hardware & software SPI options

• Author: Gavin Lyons
• Arduino IDE: 1.8.10

Output

Output Screenshots, From left to right, top to bottom.

1. Full screen bitmap displayed
2. Multi buffer mode screen divided into two horizontal buffers
3. Multi buffer mode screen divided into vertical buffers, clock demo.
4. Different size and type of fonts
5. Available ASCII font printed out 0-127
6. Extended ASCII font printed out 128-255
7. Font 1-4
8. Font 5

Installation

The library is included in the official Arduino library manger and the optimum way to install it is using the library manager which can be opened by the manage libraries option in Arduino IDE.

See link below for instruction for this and for the other methods too.

Installing Additional Arduino Libraries guide

Hardware

CH1115 is a single-chip CMOS OLED driver with controller for organic light emitting diode dot-matrix graphic display system. CH1115 consists of 128 segments, 64 commons that can support a maximum display resolution of 128 X 64. It is designed for Common Cathode type OLED panel. ER-OLEDM1.09-1W-SPI is a White 1.09" OLED Display Panel with Breakout Board. This module is a combination of the two.(controller and OLED)

pin no	pin name	pin desc
1	Gnd	Ground
2	VCC	voltage supply
3	SCL	Serial clock input
4	SDA	Serial data input
5	RES	This pin is reset signal input. When the pin is low, initialization of the chip is executed.
6	DC	This pin is Data or Command control pin.
7	CS	This pin is chip select input. The chip is enabled for MCU comms when CS is pulled low

VCC The CH1115 controller chip is a 3.3V device but the ERM LCD module has a "662k" 3.3V regulator at back. So the ERM LCD module VCC will run at 5V. It was always run it at 3.3 vcc during testing.

Logic lines The logic lines where ALWAYS connected to 3.3 Volts logic during all testing of library. The system can also run at 5 volts logic the manufacture has instruction videos connected to an Arduino Mega.

This wiring Diagram from the manufacturer datasheet showing hardware setup connected to a 3.3 volt system MCU.

Software

SPI

Hardware and software SPI. Two different class constructors. User can pick the relevant constructor, see examples files. Hardware SPI is recommended, far faster and more reliable but Software SPI allows for more flexible GPIO selection. When running Software SPI it may be necessary on very fast high frequency MCU's to change the ERMCH1115_HIGHFREQ_DELAY define, It is a microsecond delay by default it is at 0. All the hardware SPI settings are defined in the header file and can be easily changed if necessary.

buffers

3 buffer modes

1. MULTI_BUFFER (default)
2. SINGLE_BUFFER
3. NO_BUFFER , Text only, light weight.

To switch between modes, user must make a change to the USER BUFFER OPTION SECTION at top of ER_OLEDM1_CH1115.h file. Pick ONE option and one option ONLY. The example files at top, say which option to pick. If wrong option is picked, example files will not work or maybe even compile. Bitmaps can still be written directly to screen in NO_BUFFER mode but no graphics possible.

fonts

There are five fonts. A print class is available to print out most passed data types. The fonts 1-4 are a byte high(at text size 1) scale-able fonts, columns of padding added by SW. Font 5 is a special large font but it is numbers only and cannot be scaled(just one size).
Font 5 will print just numbers + semi-colons , if you print a float using print command it will place a space and use a circle for a decimal point.

Font data table:

Font num	Font name	Font size xbyy	ASCII range	Size in bytes
1	Default	5x8	Full Extended ASCII 0 - 0xFF	1275
2	Thick	7x8	no lowercase letters , ASCII 0x20 - 0x5A	406
3	Seven segment	4x8	ASCII 0x20 - 0x7A	360
4	Wide	8x8	no lowercase letters, ASCII 0x20 - 0x5A	464
5	Big Nums	16x32	ASCII 0x30-0x3A ,Numbers + : only	704

By default only Font 1 is commented in and ready to go to save memory. So to use a non-default Font (2-5), two steps.

1. Comment in the respective define at top of library header file ER_OLEDM1_CH1115_font.h in the USER FONT OPTION ONE section
2. Call SetFontNum function and pass it number of respective font. eg SetFontNum(2)

font mods

The default ASCII font (font one) is an extended font, 0-255 characters. If you do not need characters 127-255 and wish to save memory space: In library header file ER_OLEDM1_CH1115_font.h in the USER FONT OPTION TWO section Simply comment this define out.

1. UC_FONT_MOD_TWO (save 640 bytes) extended ASCII 127-255

You can also remove the first 30 characters if not needed but user will need to change ERMCH1115_ASCII_OFFSET from 0x00 to 0x20. This will save a further 150 bytes.

bitmaps

Bitmaps are written directly to screen, not buffer, Updating the buffer will overwrite them(unless bitmap set to buffer) so to share screen with text and graphics best to divide screen into buffers using multi buffer mode, See examples files. Bitmaps can be turned to data here at link , use vertical addressing draw mode.

User adjustments

When the user calls OLEDbegin() to start OLED they can specify a contrast setting from 0x00 to 0xFF. Datasheet says 0x80 is default. User can also change contrast on the fly. Screen can be disabled to enter a sleep type mode where OLED draws 500uA. Screen pixel colour can be inverted and also screen can be vertically rotated.

There is a "fade or breath display effect". Whose parameters(time brightness) can be adjusted by passing data to function see "OLEDfadeEffect" function header in .cpp and datasheet for details. default is 0x81.

There is a Horizontal scroll effect. Whose parameters: Time-interval , direction , mode, can be adjusted by passing data to function see "OLEDscrollSetup" function header in .cpp and datasheet for details. defaults are : 6 frames , right , continuous mode.

Files

X = ER_OLEDM1_CH1115 in tables below

Src Files	Desc
X.h	library header file
X.cpp	library source file
X_graphics.h	graphics header file
X_graphics.cpp	graphics source file
X_graphics_font.h	font data file

The example files are setup for an arduino UNO/NANO for the pin connections used for other MCU's during testing see extras folder, GPIO_MCU_used.txt file.

Examples files ino	Desc	Buffer mode
X_HELLO	Helloworld	MULTI_BUFFER
X_MBUF	Shows use of multi buffer mode	MULTI_BUFFER
X_MISC	Text + graphics & misc functions, rotate , scroll, etc	MULTI_BUFFER
X_BITMAP	Shows use of bitmaps	Several, see setup notes in file
X_CLOCK	clock MULTI_BUFFER demo	Several, see setup notes in file
X_NOBUF	Shows use of no buffer text only mode	NO_BUFFER
X_ONEBUF	Shows use of single buffer mode	SINGLE_BUFFER
X_SWSPI	Shows use of software SPI	MULTI_BUFFER

Tested_MCU

Tested on following MCUs.

1. Arduino UNO & NANO Example
2. ESP8266
3. ESP32
4. STM32 "blue pill"

Ports

Raspberry pi , C++

PIC-32 , C XC32